And a sexual abuse counselling service has said it is facing a vast increase in calls about online abuse and blackmail.

The girl was contacted on a social media network by a fake representative of a well-known Belfast modelling agency.

She was initially asked for general photographs, but became suspicious when she was requested to send revealing images, police said.

Chief Inspector Alan Hutton issued a warning of the incident on Facebook yesterday.

He said: "We have had a report of a 16-year-old girl being asked to send revealing photographs when contacted on a social media network by a 'representative' of a well-known modelling agency.

"The contact started off innocently enough with the girl being asked for general photographs of herself. She, rightly, became suspicious when asked for more revealing shots.

"We have made inquiries with the modelling agency, which has no knowledge of the woman who purported to work for them."

Police warned that genuine agencies did not conduct their business like this.

They said: "If you are interested in a modelling career, contact an agency personally and talk to them face-to-face. And, some general advice: never post or send revealing photos of yourself online. You do not know who is accessing them or where they will end up.

"Genuine agencies have their own means of recruiting models. Never agree to meet anyone from a 'modelling agency' unless it is at the agency's registered office.

"Genuine agencies will never ask inexperienced young people to provide intimate photographs of themselves."

Pam Hunter, chief executive of Nexus, which offers support service for survivors of sexual abuse, is facing an avalanche of calls for help in Northern Ireland.

She said: "We are seeing it more and more as children have access to the internet on their phones, on their wrists and in their bags, which makes parental supervision very difficult.

If you have been affected by these issues, Nexus NI can be contacted via nexusni.org or contact the PSNI on 101